Olefin metathesis provides a powerful tool for transforming certain natural oil compounds or their derivatives into higher-value chemical compounds, such as 9-decenoic acid and esters thereof. Such processes can include reacting a natural oil or its derivative in the presence of a metathesis catalyst.
In some instances, the process involves homogeneous catalysis, which makes it difficult to recover the used catalyst by simple filtering. Catalyst loss can therefore detract from the economic viability of the metathesis process, especially if the catalyst is expensive or in short supply. Therefore, it can be desirable to develop means of recovering at least a portion of the used catalyst from the reaction products and thereby enhance the economic viability of the process. In some instances, the used catalyst is at least partially soluble in aqueous media, and may therefore be separated from the metathesized product by contacting the metathesized product composition with a wash solution.
The wash solution may also capture other water-soluble species in the metathesized product composition. For example, aldehydes, such as formaldehyde, can be present in the metathesized product composition, and pass into the wash solution when the metathesized product is subjected to an aqueous wash. Further, in some instances, certain phosphonium salts can be present in the metathesized product composition, which also pass into the wash solution during washing. These phosphonium salts can be generated as part of the catalyst deactivation process.
Species such as formaldehyde and phosphonium salts may cause environmental harm. Thus, their presence in a wash solution may limit disposal options and therefore increase the cost of the process. It can therefore be desirable to develop methods of chemically treating the wash stream to convert these species to more innocuous species, and thereby widen the potential disposal options.
Thus, there is a continuing need to develop methods of treating metathesis biorefinery wash streams, so as to recover catalyst and/or reduce the toxicity of certain species that may be present in such wash streams.